Cable drop compensation circuit and power circuit using the same

Abstract

A cable drop compensation circuit includes a current detection circuit, a compensation judgment circuit, and a compensation circuit. The current detection circuit detects a load current supplied to a load by a DC output circuit, so as to generate a current detection signal. The compensation judgment circuit receives the current detection signal, and generates a judgment signal when judging the load current higher than a predetermined compensation value. When receiving the judgment signal, the compensation circuit generates a compensation signal. In response to the compensation signal, the DC output circuit raises an output voltage by a compensation voltage.

The invention claimed is: 
     
       1. A cable drop compensation circuit, comprising:
 a current detection circuit, detecting a load current supplied by a DC output circuit to a load and generating a current detection signal; 
 a compensation judgment circuit, receiving the current detection signal and generating a judgment signal when judging the load current higher than a predetermined compensation value; and 
 a compensation circuit, generating a compensation signal when receiving the judgment signal; 
 wherein the DC output circuit raises an output voltage by a compensation voltage in response to the compensation signal. 
 
     
     
       2. The cable drop compensation circuit of  claim 1 , wherein the compensation voltage is a constant ratio of the output voltage, regardless of the load current. 
     
     
       3. The cable drop compensation circuit of  claim 1 , further comprising a protection circuit, the protection circuit comprising:
 a switch coupled between the DC output circuit and the load; and 
 an overcurrent judgment circuit for cutting off the switch to stop the load current being supplied to the load when the load current is higher than an overcurrent protection value. 
 
     
     
       4. The cable drop compensation circuit of  claim 3 , wherein the current detection circuit, the compensation judgment circuit, the compensation circuit and the protection circuit are encapsulated within a single package, the compensation judgment circuit being coupled to a compensation setting component via a first pin of the package and determining the predetermined compensation value in accordance with the compensation setting component, and the protection circuit being coupled to an overcurrent setting component via a second pin of the package and determining the overcurrent protection value in accordance with the overcurrent component. 
     
     
       5. The cable drop compensation circuit of  claim 1 , wherein the current detection circuit, the compensation judgment circuit and the compensation circuit are encapsulated within a single package, the compensation judgment circuit being coupled to a setting component via a pin of the package and determining the predetermined compensation value in accordance with the setting component. 
     
     
       6. The cable drop compensation circuit of  claim 1 , wherein the current detection circuit, the compensation judgment circuit, the compensation circuit and the DC output circuit are encapsulated within a single package, the compensation judgment circuit being coupled to a setting component via a pin of the package, determining the predetermined compensation value in accordance with the setting component. 
     
     
       7. The cable drop compensation circuit of  claim 6 , wherein the compensation voltage is proportional to the load current. 
     
     
       8. A power circuit with cable drop compensation, comprising:
 a DC output circuit for providing an output voltage and adjusting the output voltage according to a feedback signal; and 
 at least two cable drop compensation circuits respectively coupled between the DC output circuit and a corresponding load, each of the cable drop compensation circuit comprising:
 a current detection circuit, detecting a load current of the corresponding load and generating a current detection signal accordingly; 
 a compensation judgment circuit, receiving the current detection signal and generating a judgment signal when judging the load current greater than a predetermined compensation value; and 
 a compensation circuit generating a compensation signal when receiving the judgment signal; 
 
 wherein the DC output circuit raises the output voltage by a compensation voltage in response to at least one of the compensation signals. 
 
     
     
       9. The power circuit with cable drop compensation circuit of  claim 8 , wherein the compensation voltage is raised in a stepwise manner corresponding to the number of the compensation signals generated by the cable drop compensation circuits. 
     
     
       10. The power circuit with cable drop compensation of  claim 8 , wherein each of the cable drop compensation circuit is coupled to the feedback signal via a diode. 
     
     
       11. The power circuit with cable drop compensation of  claim 8 , wherein the DC output circuit raises the output voltage by the compensation voltage when any cable drop compensation circuit generates the compensation signal, and the compensation voltage is a constant ratio of the output voltage, regardless of a number of the compensation signal. 
     
     
       12. The power circuit with cable drop compensation of  claim 8 , wherein each of the cable drop compensation circuit further comprises a protection circuit, the protection circuit comprising:
 a switch coupled between the DC output circuit and the corresponding load; and 
 an overcurrent judgment circuit for cutting off the switch to stop the load current flowing to the corresponding load when the load current of the corresponding load is higher than an overcurrent protection value. 
 
     
     
       13. A cable drop compensation circuit, coupled to a DC output circuit, and outputting a compensation output voltage, the cable drop compensation circuit comprising:
 a current detection circuit detecting a load current supplied to the load by the DC output circuit and generating a current detection signal accordingly; 
 a compensation circuit for generating a compensation signal according to the current detection signal; and 
 a feedback control circuit for adjusting a voltage across a transistor according to a compensation signal and a feedback signal representing the compensation output voltage, wherein the transistor is coupled between the DC output circuit and the load. 
 
     
     
       14. A cable drop compensation circuit of  claim 13 , further comprising a protection circuit, wherein the protection circuit cuts off the transistor to stop the load current supplied to the load when the compensation output voltage is higher than an overcurrent reference voltage. 
     
     
       15. The cable drop compensation circuit of  claim 14 , wherein the current detection circuit, the feedback control circuit, the compensation circuit and the protection circuit are encapsulated within a single package, the compensation circuit coupled to a compensation setting component via a first pin of the package, and the protection circuit coupled to an overcurrent setting component via a second pin of the package and determining the overcurrent protection value in accordance with the overcurrent setting component.